Production lines typically incorporate metrology measurements on representative samples and/or locations on samples to monitor process variations and ensure that fabrication remains within quality tolerances. Accordingly, metrology recipes defining the number, location, and frequency of metrology measurements are typically carefully designed to balance the accuracy of metrology measurements, the number of representative metrology measurements, and the measurement throughput to achieve a desired level of fabrication accuracy within a reasonable timeframe. Metrology throughput is therefore a critical consideration in semiconductor metrology systems and increases in metrology throughput may facilitate tighter process control and/or increased total production throughput of a semiconductor process.
Multilayer film stacks such as, but not limited to, three-dimensional (3D) flash memory devices present particular challenges that may limit metrology throughput since each layer is typically not directly characterized. For example, multilayer film metrology typically relies on modeling to extract parameters of interest (e.g., average film thickness, or the like) from a measurement. It may therefore be desirable to provide a system and method for efficient multilayer metrology.